The invention relates to a method for determining the driving resistance of a vehicle.
Due to dwindling resources and simultaneously increasing environmental awareness, it is increasingly important to develop as much as possible environmentally friendly vehicles. Very low emission levels can be achieved with hybrid vehicles that are equipped with an electric motor and an internal combustion engine. Especially with hybrid vehicles, but also with other vehicles, it is important for the driver to know the remaining driving range based on the current energy storage contents or the fuel quantity. Especially important for determining the residual driving range is the driving resistance of a vehicle, which is dependent on the number of occupants, the load, the type of the tires, and additional vehicle characteristics.
The exact knowledge of the driving resistance of a vehicle under different operating conditions can also be used for control tasks within the vehicle. For example, DE 10 2006 022 170 A1 discloses a method for determining the driving resistance of a vehicle wherein, in conjunction with an automatic transmission, driving resistance values are determined before the start of a gear shift and at a later time. If a change in driving resistance is detected in this context, the shifting operation can be corrected if necessary.
DE 601 13 226 T2 discloses a method for determining the driving resistance of a vehicle under the assumption of constant driving resistance coefficients and a predetermined vehicle mass. While driving, a threshold comparison is carried out which can be used to iteratively and more precisely determine driving resistance coefficients and the vehicle mass. However, only stored constants are used in these known methods to calculate the driving resistance at the beginning of the trip.
It is the object of the invention to provide a method for determining the driving resistance of a vehicle, which is capable of providing accurate information about the actual driving resistances and the mass of the vehicle at the beginning of the trip and while driving continues.